#include<bits/stdc++.h>
#include <pthread.h>
using namespace std;

class Single_model_lan_han
{
private:
    /* data */
    Single_model_lan_han(/* args */){};
    Single_model_lan_han(const Single_model_lan_han& other){};
    Single_model_lan_han& operator=(const Single_model_lan_han& other){
        return *this;
    }
    static Single_model_lan_han* ins;
public:
    static pthread_mutex_t mutex;
    Single_model_lan_han* get(){
        if(ins==nullptr){
            pthead_mutex_lock(&mutex);
            if(ins==nullptr){
                ins = new Single_model_lan_han();
            }
            pthead_mutex_unlock(&mutex);
        }
        return ins;
    }
    ~Single_model_lan_han(){};
};




int main(int argc, char const *argv[])
{
    /* code */
    return 0;
}
